Electrolytic process



W. E. GREENAWALT.

ELECTROLYTIC PROCESS.

APP LIQATION FILED JAN. l9. I914. RENEWED DEC. 26.1918.

1,314,742. Patented Sept. 2, 1919.

2 SHEETS-SHEET l- 1s l o 7 41 10+ \l I 2 2 g 18 2 i 20 9 9 5 a 5 i 1 31742 i i 9' 1 2 i 4 n 1 V RC2 VVz'Zzzesses Invenfor W. E. GREENAWALT.

ELECTROLYTIC PROCESS.

APPLICATION men 1AN.19.1914. RENEWED DEC-26,1918. 1,314,742.

Patented Sept. 2, 1919.

2 SHEETSSHEET 2.

T/Vz'fflesses In ven Zor UNITED STATES PATENT OFFICE.

WILLIAM E. GBEENAWALT, OF DENVER, COLORADO.

ELECTROLYTIC rnocnss.

Specification of Letters Patent.

Patented Sept. 2, 1919.

Application filed January 19, 1914, Serial No. 812,951. Renewed December26, 1918. Serial No. 268,415.

To all whom it may concern:

Be it known that I, WILLIAM E. GREENA- WALT, a citizen of the UnitedStates, residing in the city and county of Denver and the State ofColorado, have invented cerin leaching copper ores, there is alwaysresent iron sulfate, which injuriously a ects the operation. Ferroussulfate is not particularly harmful in the electrolyte, but the ferricsulfate is highly detrimental. I

If a solution of copper sulfate, containing ferrous sulfate, iselectrolyzed, copper is deposited at the cathode while sulfuric acid andferric sulfate are produced atthe anode, as represented by thefollowing. equations:

The ferric sulfate, finding its way back to the cathode, combines withthe deposited copper and is again reduced to the ferrous condition, thusrepresenting a loss of efficiency, as represented by equation:

If, however, the ferric sulfate can be reduced at the expense of a cheapreducing agent, such as sulfur dioxid, then acid is regenerated and theiron in the electrolyte loses its ability to combine with the depositedcopper, as shown by equation:

sothat for every' molecule of iron that is reduced from the ferric tothe ferrous condition two molecules of acid are regenerated. This acidis beneficial in the electrolyte, and on leaving the electrolyzer isfurther avail able for the extraction of copper from the ore.-

Similarly, if there is an excess of sulfur dioxid in the electrolyte, itacts as a depolarizer and acid generator, thus:

The effectiveness of these reactions and the practical results obtained,depends upon the thoroughness with which the sulfur dioxid is brought incontact with the electrolyte. In my process this is effectively andcontinuously accomplished, as will now be explained by referring to theaccompanymg drawings, in which Figure 1 represents a plan through theapparatus illustrating the process;

Fig. 2, the corresponding longitudinal section;

gig. 3, the plan of a modified apparatus, an

Fig. 4, the corresponding section.

In the figures, 1 is a tank containing the electrolyte, which may bepresumed to be copper sulfate solution as obtained, say, from leachingcopper ores. 2 are the anodes, and 3 the cathodes, 4 is a frame hav ingstirring bars 5 interposed between the electrodes, preferablyoscillating as a whole, and suspended from fixed pivotal points 6, andactuated by the mechanism 7.

10 represents the mechanism, taken as a whole, by means of whichreducing gases, such as sulfurdioxid, are brought to a mi nute state ofsubdivision, or atomized, in contact with theele'ctrolyte, and consists,preferably, of an outer tank 9, into which the electrolyte flows fromthe cell through the pipe 8. Inserted within the tank 9, is a tube 11,havin perforated disks 12, and is suspended within the tank by the-shaft13-from the ball bearings 14. This tube is made to revolve at a highspeed, being driven by the pulley 15, and the motor 16. The reducinggas, say, sulfur dioxid, is produced in the generator 17 and by means ofthe air or gas pump 18, is forced through the pipe 19, and into the tube11, of the atomizer, 10. 20 is the return pipe for the reduced solution,and 21 the exhauster for the excess gas, and air or nitrogen, throughthe pipe 22, toprevent it from getting into the cell room andcontaminating the atmosphone. Or the excess gas may be forced throughanother apparatus in connection with another cell. i

To operate the process, the electrolyte may be presumed to be chargedinto the cell depolarizer. If the action at the anode were allowed tocontinue the reducing agent would soon be exhausted and the ironoxidized to the ferric condition, which would be highly injurious andgreatly reduce the current efliciency. To avoid this a portion of theelectrolyte is allowed to flow into the atomizer 10 while at the sametime the reducing gas from the generator 17, is forced into the tube 11,which is revolved at a high speed, so that the gas ascending through.the

tube 11, and perforated disks is divided into minute particles, oratomized, in contact With the solution, and thoroughly incorporated withit, thus making it possible to quickly, eflectively, and continuouslyreduce the solution, and if desired, charge it with an excess of thegas. It is then again returned, preferably though not necessarily,

in a continuous stream to the electrodes. In this way the injuriousferric compounds are kept at a minimum or entirely avoided. The gasascending through the tube 11, acts as an air lift, thus making itpossible to return the reduced electrolyte at a higher level than thelevel of the electrolyte at the electrodes. The circulation may thus beaccomplished by gravity and by the buoyant action of the atomized gas inthe liquid.

Reducing gases, such as sulfur dioxid, are only slightly soluble inwater, but by the arrangement of the present process this difficulty isovercome since the gas may be continuously applied to the electrolyteand the accumulation of the injurious ferric compounds, in injuriousamounts, prevented.

As a modified arrangement, shown in Figs. 3 and 4, the atomizer might beinserted in the electrolyte tank 1, in a space reserved in the cell forthe purpose. In either case a portion of the electrolyte is temporarilysegregated from the electrodes and from the main body of the electrolyteand treated with the reducing gases and then again returned to theelectrodes. I

The process permits of considerable gen eration of acid and theretaining of the acid in the electrolyzer to a much greater extent thanis ordinarilv possible. This is a highly desirable feature, as theincreased acidity, and to a certain extent the accompanying increasedtemperature also, greatly reduces the electromotive force required forthe deposition of the copper. The excess regeneration of acid is alsodesirable as a solvent of copper from the ore, since more acid can bethen wasted without detriment and the elec trolyte kept in a higherstate of purity, and consequently of efliciency.

The process presents marked advantages fectively in contact. with theelectrodes as rapidly as it is reduced, and this action is made moreeffective by the circulation of the electrolyte. In Fig. 4 thecirculation is made more effective by introducing the gas into one endof the pipe 30, thus acting as an injector, and taking the electrolytefrom the further end of the cell, while the reduced electrolyte flows inthe opposite direction.

The effective depolarization brought about by this process by the use ofsulfur dioxid and ferrous sulfate produces large quantities of acid,reduces the E. M. F. for the deposition of the copper, and greatlyprolongs the life of the insoluble anodes. The

life of the anodes depends largely on the effectiveness of thedepolarization.

I claim:

1. An electrolytic process which consists in electrolyzing coppersolutions containing ferrous salts to deposit the copper at the cathodewith a simultaneous oxidation of the ferrous salts to the ferric saltsat the anode, agitating the electrolyte, segregating a portion of theelectrolyte from the elec-' trodes, applying to the segregatedelectrolyte a gas capable of reducing the ferric salts to the ferrouscondition so as to rise through the electrolyte by its own buoyancy inthe liquid, atomizing the gas in contact with the electrolyte as itascends through the liquid, and returning the reduced electrolyte to theelectrodes. i

2. An electrolytic process which consists in electrolyzing coppersolutions containing ferrous salts to deposit copper at the cathode witha simultaneous oxidation of the ferrous salts to the ferric salts at theanode, segregating a portion of the electrolyte from the electrodes,applying to the segregated electrolyte a gas capable of reducing theferric salts to the ferrous condition so as to rise through theelectrolyte by its own buoyancy in the liquid, atomizing the gas incontact.

with the electrolyte as it ascends through the liquid, and returning thereduced electrolyte to the electrodes.

3. An electrolytic'pro'cess which consists in electrolyzing coppersolutions containing ferrous salts to deposite copper at the oathodewith a simultaneous oxidation of the ferrous salts to the ferric saltsat the anode, withdrawing a portion of the electrolyte containin ferricsalts from the electrolyzer and intr ucing it into a reducing chamber,applying a gaseous reducing agent to the segregated portion of theelectrolyte to rise through the liquid by its own buoyancy in theliquid, atomizing the gas in contact with the segregated electrolyte asit ascends through the liquid whereby the ferric salts is again reducedto the ferrous condition, and circulating the electrolyte between theelectrolyzer and the reducing chamber by the buoyant action of theatomized gas in the electrolyte in the reducing chamber.

7 4:. An electrolytic process which consists in electrolyzing coppersolutionscontaining ferrous salts to deposit the copper at the cathodewith the simultaneous oxidation of the ferrous salts to the ferric saltsat the anode, segregating a portion of the electrolyterfrom theelectrodes, applying sulfur dioxid to the segregated electrolyte toreduce the ferric salts to the ferrous condition and' in such a way asto rise through the electrolyte by its own buoyancy in theliquidyatomizing the gas in contact with the electrolyte as it'ascendsthrou h the liquid, and re-- turning the reduced "e ectrolyte containingan excess of the gas to the electrodes.

5. An electrolytic process which consists in electrolyzing coppersolutions containing ferrous salts to deposit the copper at the cathodewith the simultaneous oxidation of the ferrous salts to the ferric saltsat the v anode, applying a reducin gas to a 001 of the electrolyte in are ucing cham ber, maintainin a flow of gas in the reducing chamber, sudividing the as in the electrolyte in the reducing cham er, andexhausting the excess gas from the reducing cham- A ber of oneelectrolyzer and appl ing it to the electrolyte in the reducing c amberof another electrolyzer. 4 r

6. An electrolytic process which consists in electrolyzing coppersolutions containing ferrous salts to deposit the copper at the cathodewith the simultaneous oxidation of the ferrous salts to the ferric saltsat the anode, segregating a portion of the electrolyte from theelectrodes into a reducing chamber, applying a reducing gas to theelectrolyte in the reducing chamber to reduce the ferric salts to theferrous salts, subdividing the gas in the reducing chamber, and applyinga stream of gas to a stream of lyte from t e electrodes into a reducingchamber, ap lying a reducing gas to the segregated e ectrolyte so thatit will rise through the electrolyte by the pressure of the liquid onthe gas, thus causing a higher liquid level in the reducing chamber thanin theelectrolyte tank, subdividing the as in its ascent through thesegregating e ectrolyte in the reducing chamber, and maintaining acontinuous flow of reduced electrolyte from the reducing chamber to theelectrodes and of oxidized electrolyte from the electrodes to thereducing chamber.

8. An electrolytic process which consists in electrolyzing coppersolutions containing salts'of iron to deposit the copper at the cathodewith the simultaneous oxidation of the ferrous salts to the ferric saltsat the anode, maintaining a continuous fiow of electrolyte from theelectrolyzerto a reducing chamber, applying a reducing gas to the theelectrolyte by the pressure of the liquid 7 on the gas, subdividing thegas in its ascent through the electrolyte, and maintaining the flow ofelectrolyte by the difference in the liquid level induced by theapplication of the gas in the reducing chamber.

9. An electrolytic process which consists in electrolyzing coppersolutions containing salts of iron to deposit the copper at the cathodewith the simultaneous oxidation of theferrous salts to the ferric saltsat the anode, applying a reducing gas to a pool of the electrolyte in areducing chamber, treating the electrolyte with the gas by intimatelymixing the gas with the electrolyte in the pool, maintaining a flow ofgas through the reducing chamber, and maintaining a flow of reducedelectrolyte from the pool in the reducing chamber to the electrodes andof oxidized electrolyte from the electrodes to the pool.

WILLIAM E. GREENAWALT.

Witnesses:

THOMAS S. WALTEMEYER, EDWIN J. Omssunn.

